1. Field of the Invention
The present invention relates, in general, to the field of temperature indicators and, more particularly, this invention relates to an apparatus for determining whether the temperature of a pressurized fluid contained in a container (or flowing through a conduit) has, at some previous time, exceeded a specified temperature. Even more particularly, the present invention relates to an apparatus for indicating whether the temperature of a gas (e.g., air) within a container or conduit has exceeded such a specified temperature. The present invention is seen to have particular application to determining whether air flowing in a conduit between a low pressure cylinder and a high pressure cylinder of a two-stage air compressor having an integral intercooler provided therebetween has exceeded a specified temperature.
2. Description of the Related Art
As is generally well known in the art, fluids at elevated temperatures are present in many types of processes and apparatuses and keeping the fluids within particular temperature ranges can be essential to a proper functioning of these processes and apparatuses. The fluid having exceeded, at some prior time, a specified temperature can possibly indicate a malfunction which should be investigated.
As is explained more fully below, a well known air compressor unit employed extensively in the rail transportation industry uses a two-stage compression, with air from a low compression cylinder passing through an integrally provided intercooler prior to introduction into a high compression cylinder. At least a portion of the air may be routed so as to bypass the intercooler, particularly upon initial startup, to prevent the air introduced into the high pressure cylinder from being "overcooled", which can create problems due to excess condensation forming in the intercooler.
The amount of air which is actually routed through the intercooler in such a case may be controlled via a thermostatic control system. Excess temperature of the air passing through the conduit leading from the intercooler to the high pressure cylinder can be indicative of a malfunctioning of such a thermostatic control system.